Differences in areal bone mineral density between metabolically healthy and unhealthy overweight/obese children: the role of physical activity and cardiorespiratory fitness

Objectives: To examine whether areal bone mineral density (aBMD) differs between metabolically healthy (MHO) and unhealthy (MUO) overweight/obese children and to examine the role of moderate-to-vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF) in this association. Methods: A cross-sectional study was developed in 188 overweight/obese children (10.4 ± 1.2 years) from the ActiveBrains and EFIGRO studies. Participants were classified as MHO or MUO based on Jolliffe and Janssen’s metabolic syndrome cut-off points for triglycerides, glucose, high-density cholesterol and blood pressure. MVPA and CRF were assessed by accelerometry and the 20-m shuttle run test, respectively. Body composition was measured by dual-energy X-ray absorptiometry. Results: In model 1 (adjusted for sex, years from peak high velocity, stature and lean mass), MHO children had significantly higher aBMD in total body less head (Cohen’s d effect size, ES = 0.34), trunk (ES = 0.43) and pelvis (ES = 0.33) than MUO children. These differences were attenuated once MVPA was added to model 1 (model 2), and most of them disappeared once CRF was added to the model 1 (model 3). Conclusions: This novel research shows that MHO children have greater aBMD than their MUO peers. Furthermore, both MVPA and more importantly CRF seem to partially explain these findings. This study has been partially funded by the University of Granada, UGR Research and Knowledge Transfer Fund (PPIT) 2016, Excellence Actions Programme: Units of Scientific Excellence; Scientific Unit of Excellence on Exercise and Health (UCEES), and by the Regional Government of Andalusia, Regional Ministry of Economy, Knowledge, Enterprises and University and European Regional Development Fund (ERDF), ref. SOMM17/6107/UGR. The ActiveBrains study was funded by the Spanish Ministry of Economy and Competitiveness (Reference DEP2013-47540, DEP2016-79512-R, and DEP2017-91544-EXP). The EFIGRO study was funded by the Spanish Ministry of Health, 'Fondo de Investigación Sanitaria del Instituto de Salud Carlos III' (PI13/01335), 'Fondos Estructurales de la Unión Europea (FEDER), Una manera de hacer Europa,' and by the University of the Basque Country (GIU14/21). L.G.-M. is supported by 'La Caixa' Foundation within the Junior Leader fellowship programme (ID 100010434); M.M. is supported by the Spanish Ministry of Education, Culture and Sport (FPU14/03329) and EST17/00210; L.A. is supported by the Education Department of the Government of the Basque Country (PRE_2016_1_0057, PRE_2017_2_0224 and PRE_2018_2_0057); J.M.-G. and J.H.M. are supported by the Spanish Ministry of Education, Culture and Sport (FPU14/06837 and FPU15/02645, respectively).